Summary CCR10 is a chemokine receptor. One of its ligand, CCL27, is predominantly expressed in the skin. The CCR10/ligand axis was suggested to play a role in directing migration and maintenance of CCR10-expressing T cells into the skin and has been implicated in many skin inflammatory diseases such as psoriasis and atopic dermatitis. However, the in vivo functional importance and mechanisms of CCR10 in regulating the cutaneous immune responses are still not clear. We have generated CCR10-knockout/EGFP-knockin mice and found that the CCR10-knockout mice have altered maintenance of skin-resident T cells and response to various skin antigen challenges. We propose to use these mouse models to study the functional mechanisms of CCR10 in regulating the skin T response and immune homeostasis.